Undercarriage and running gear

Abstract

To provide a technique of miniaturizing a chassis device using a rocker bogie mechanism.SOLUTION: A chassis device includes: a driving wheel 24; a first driven wheel 26 disposed on one side in a longitudinal direction with respect to the driving wheel 24; a second driven wheel 28 disposed on the other side in the longitudinal direction with respect to the driving wheel 24; a bogie link member 38 supporting the driving wheel 24 and the first driven wheel 26 to be rocked around a first rocking shaft 44; and a rocker link member 40 supporting the second driven wheel 28 and the bogie link member 38 to be rocked around a second rocking shaft 50. The first rocking shaft 44 is positioned vertically above a rotation shaft 70 rather than on the same vertical line as the rotation shaft 70 of the driving wheel 24 and positioned inside an outer shape of the driving wheel 24 when seen from a right-left direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an undercarriage device used in a traveling device. [Background technology]

[0002] Patent Document 1 discloses an undercarriage device using a rocker bogie mechanism that includes a bogie link member that supports a driving wheel and a first driven wheel, and a rocker link member that supports a second driven wheel and the bogie link member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-19348 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have recognized that there is room for improvement in the prior art in order to reduce the size of an undercarriage device using a rocker bogie mechanism.

[0005] One of the objects of the present disclosure is to provide a technology for reducing the size of an undercarriage device using a rocker bogie mechanism. [Means for solving the problem]

[0006] The suspension device of the present disclosure comprises a drive wheel, a first driven wheel arranged on one side of the drive wheel in the fore-and-aft direction, a second driven wheel arranged on the other side of the drive wheel in the fore-and-aft direction, a bogie link member that supports the drive wheel and the first driven wheel and is swingable around a first swing axis, and a rocker link member that supports the second driven wheel and the bogie link member and is swingable around a second swing axis, and when viewed from the left-right direction, the first swing axis is not on the same vertical line as the rotation axis of the drive wheel, but is located vertically above the rotation axis and inside the outer shape of the drive wheel. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to reduce the size of the leg mechanism using a rocker bogie mechanism.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described. The same components are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the direction of the reference numerals.

[0010] (First Embodiment) Refer to FIG. 1. The traveling device 10 is an unmanned transport vehicle such as an AGV (Automatic Guided Vehicle) or an AMR (autonomous mobile robot). The traveling device 10 includes a device main body 12 and a wheel assembly 14 attached to the device main body 12. The device main body 12 includes a mounting portion 16 for mounting an article to be transported. The device main body 12 is equipped with a control device (not shown) composed of a computer for controlling the traveling operation of the traveling device 10, a battery (not shown) for supplying power to the control device and a driving device 20 (described later), etc.

[0011] Refer to FIGS. 2, 3, and 4. FIG. 3 is also a view of a part of the wheel assembly 14 as seen from the arrow A in FIG. 2. In this specification, regarding the positional relationship of each component, the front-rear direction X, the left-right direction Y, and the up-down direction Z are used for explanation. The front-rear direction X is a horizontal direction orthogonal to the rotation axis 70 (virtual axis) that is the rotation center of the drive wheel 24 (described later), and the left-right direction Y is a horizontal direction orthogonal to the front-rear direction X. The up-down direction Z is the vertical direction.

[0012] The wheel assembly 14 includes a pair of wheel sets 18 arranged on both the left and right sides, a driving device 20 for driving the drive wheels 24 of the wheel sets 18, and a wheel base (wheel set support) 22 for supporting each of the pair of wheel sets 18.

[0013] The wheel set 18 consists of a plurality of wheels. The plurality of wheels constituting the wheel set 18 include a drive wheel 24, a first driven wheel 26 arranged on the front side (the left side in FIG. 3) which is one side of the front-rear direction X with respect to the drive wheel 24, and a second driven wheel 28 arranged on the rear side (the right side in FIG. 3) which is the other side of the front-rear direction X with respect to the drive wheel 24.

[0014] The drive wheel 24 is rotatable by the power transmitted from the driving device 20. The drive wheel 24 of this embodiment is a wheel with a tire, and includes a wheel 30 rotated by the driving device 20 and a tire 32 attached to the wheel 30. The type of the drive wheel 24 is not particularly limited, and an integral wheel or the like may be used.

[0015] Each of the driven wheels 26, 28 does not receive power from the drive unit 20 and can rotate following the rotation of the drive wheels 24. In this embodiment, each of the driven wheels 26, 28 is an integral wheel. The type of the driven wheels 26, 28 is not particularly limited, and they may be wheels with tires, etc. In this embodiment, the first driven wheel 26 is a front wheel located on the front side, and the second driven wheel 28 is a rear wheel located on the rear side.

[0016] The drive unit 20 in this embodiment is a gear motor. Specific examples of the drive unit 20 are not particularly limited, and may be a motor, an engine, etc. The drive unit 20 includes a casing 34 fixed to a bogie link member 38 (described later) by bolts or the like. The casing 34 penetrates the bogie link member 38 in the left-right direction Y. The drive unit 20 is disposed inside the drive wheels 24 in the left-right direction Y. The drive unit 20 includes an output member 36 fixed to the wheel 30 of the drive wheel 24 by bolts or the like, and capable of outputting rotational power. The drive wheels 24 are rotated by power being directly transmitted from this output member 36.

[0017] The pair of wheel bases 22 are disposed with a gap between them in the left-right direction Y. The wheel base 22 includes a bogie link member 38 that supports the driving wheels 24 and the first driven wheel 26, and a rocker link member 40 that supports the second driven wheel 28 and the bogie link member 38. Each link member 38, 40 of the wheel base 22 is made of a metal such as stainless steel or aluminum.

[0018] The bogie link member 38 is an elongated member that is long in the longitudinal direction X. The bogie link member 38 is connected to the first driven wheel 26 at one end (front end) in the longitudinal direction X, and is connected to the driving wheel 24 at the other end (rear end) on the opposite side in the longitudinal direction X. As described above, the bogie link member 38 is connected to the driving wheel 24 via the drive unit 20.

[0019] The bogie link member 38 is connected to the rocker link member 40 via a first support bearing 42 so as to be swingable with relative rotation about a first swing shaft 44. The first swing shaft 44 is an imaginary axis that serves as the swing center of the bogie link member 38. "Swing" here refers to rotation of the referenced link member (here, the bogie link member 38) around the referenced swing shaft as the swing center when viewed from the left-right direction Y.

[0020] The first support bearing 42 is, for example, a cross roller bearing. The first support bearing 42 includes a first outer ring 42a, a first inner ring 42b, and a plurality of first rolling elements (not shown) that roll on the first outer ring 42a and the first inner ring 42b. The bogie link member 38 is provided with a first accommodating recess 46 in its intermediate portion in the fore-and-aft direction X, at a location facing the rocker link member 40 in the left-right direction Y. The first support bearing 42 is accommodated in the first accommodating recess 46. The first outer ring 42a of the first support bearing 42 is fixed to the bogie link member 38 with screws or the like, and the first inner ring 42b is fixed to the rocker link member 40 with screws or the like. As a result, the first support bearing 42 connects the bogie link member 38 to the rocker link member 40 in a swingable manner. A first swing shaft 44, which serves as the swing center, is located on the axis of the first support bearing 42.

[0021] The rocker link member 40 is an elongated member that is long in the fore-and-aft direction X. The rocker link member 40 is connected to the bogie link member 38 at one end (front end) in the fore-and-aft direction X, and is connected to the second driven wheel 28 at the other end (rear end) on the opposite side in the fore-and-aft direction X.

[0022] The rocker link member 40 is connected to the device body 12 via a second support bearing 48 so as to be able to swing with relative rotation about a second swing axis 50. In this embodiment, the rocker link member 40 is connected to the device body 12 via an attachment member 52 for attaching it to the device body 12, in addition to the second support bearing 48. The second swing axis 50 is a virtual axis that serves as the swing center of the rocker link member 40.

[0023] The second support bearing 48 is, for example, a cross roller bearing. The second support bearing 48 includes a second outer ring 48a, a second inner ring 48b, and a plurality of second rolling elements 48c that roll on the second outer ring 48a and the second inner ring 48b. The rocker link member 40 includes a second accommodating recess 54 that is recessed in the left-right direction Y and is provided at its intermediate portion in the front-rear direction X, facing the mounting member 52 in the left-right direction Y. The second support bearing 48 is accommodated in the second accommodating recess 54. The second outer ring 48a of the second support bearing 48 is fixed to the rocker link member 40 with screws or the like, and the second inner ring 48b is fixed to the mounting member 52 with screws or the like. As a result, the second support bearing 48 connects the rocker link member 40 to the device main body 12 via the mounting member 52 in a swingable manner. A second swing shaft 50, which serves as the swing center, is provided on the axis of the second support bearing 48.

[0024] The bogie link members 38 and rocker link members 40 of the wheelbase 22 constitute a rocker bogie mechanism. When traveling on uneven ground, such as uneven or undulating terrain, the rocker bogie mechanism swings the link members 38 and 40 around the swing shafts 44 and 50 to follow the shape of the running surface 56, thereby keeping the three wheels (the driving wheel 24 and each of the driven wheels 26 and 28) in contact with the running surface 56. This prevents any of the three wheels from lifting off the running surface 56, ensuring high stability when traveling on uneven ground. The operating principle of this rocker bogie mechanism is well known, so a detailed description thereof will be omitted here.

[0025] The undercarriage device 14 includes a rotation support mechanism 62 that supports the driven wheels 26, 28 rotatably around a rotation axis 60 that extends up and down (vertically). The rotation axis 60 is an imaginary axis that serves as the rotation center of the driven wheels 26, 28, and in this embodiment, is a vertical axis. The undercarriage device 14 of this embodiment includes individual rotation support mechanisms 62 that correspond to the first driven wheel 26 and the second driven wheel 28. In this embodiment, the rotation support mechanism 62 that corresponds to the first driven wheel 26 and the rotation support mechanism 62 that corresponds to the second driven wheel 28 have a common configuration, so the configuration of the former will be mainly described and a description of the latter will be omitted.

[0026] The swivel support mechanism 62 connects the driven wheels 26 and 28 to the wheelbase 22 so as to be rotatable around the rotation axis 60. The first driven wheel 26 is connected to the bogie link member 38 of the wheelbase 22 by the swivel support mechanism 62. The second driven wheel 28 is connected to the rocker link member 40 of the wheelbase 22 by the swivel support mechanism 62. In the present embodiment, the swivel support mechanism 62 and the driven wheels 26 and 28 function as swivel casters. The swivel support mechanism 62 includes a wheel support 64 that rotatably supports the driven wheel 26 around the axis of the driven wheel 26, 28, and a rotary connection mechanism 66 that rotatably connects the wheel support 64 to the wheelbase 22. The wheel support 64 is configured using, for example, a fork or the like. The rotary connection mechanism 66 of the present embodiment is configured by a rotary joint (swivel joint). The axis 29 of each of the driven wheels 26 and 28 is arranged at a position offset from the rotation axis 60. Thereby, it is possible to shift the intersection of the rotation axis 60 with respect to the traveling surface 56 and the ground contact points of the driven wheels 26 and 28 to secure a caster trail. Therefore, when the traveling device 10 travels, it becomes easier to align the traveling direction of the traveling device 10 with the directions of the driven wheels 26 and 28, and good straight-ahead stability can be obtained.

[0027] Refer to FIG. 3. Hereinafter, the positional relationship of each component as viewed from the left-right direction Y will be described. Let La be the front-rear dimension from the rotation axis 70, which is the rotation center of the drive wheel 24, to the first swing axis 44. Let Lb be the front-rear dimension from the first swing axis 44 to the connection position of the first driven wheel 26 to the bogie link member 38 (in the present embodiment, the rotation axis 60 of the first driven wheel 26). Let Lc be the front-rear dimension from the connection position of the second driven wheel 28 to the rocker link member 40 (in the present embodiment, the rotation axis 60 of the second driven wheel 28) to the second swing axis 50. Let Ld be the front-rear dimension from the second swing axis 50 to the first swing axis 44. Let Le be the front-rear dimension from the second swing axis 50 to the connection position of the first driven wheel 26 to the bogie link member 38. In the present embodiment, La = Ld, but these may be different. The front-rear dimension here refers to the dimension along the front-rear direction X.

[0028] Let the upward vertical reaction forces acting on each of the wheels 24, 26, and 28 from the running surface 56 be Fa, Fb1, and Fb2. Fa is the vertical reaction force of the drive wheel 24, Fb1 is the vertical reaction force of the first driven wheel 26, and Fb2 is the vertical reaction force of the second driven wheel 28. When using a rocker bogie mechanism, it is known that the ratio of the vertical reaction forces Fa, Fb1, and Fb2 (hereinafter referred to as the reaction force ratio) can be controlled according to the ratios of La:Lb and Lc:Ld (hereinafter referred to as the length ratio).

[0029] When the moments around the first swing axis 44 due to the vertical reaction forces Fa and Fb1 acting on the bogie link member 38 are balanced, Fa×La = Fb1×Lb, and it can be rewritten as La:Lb = Fb1:Fa ··· (A). Also, when the moments around the second swing axis 50 due to the vertical reaction forces Fa, Fb1, and Fb2 acting on the rocker link member 40 are balanced, Fb2×Lc = (Fa + Fb1)×Ld, and it can be rewritten as Lc:Ld = (Fa + Fb1):Fb2 ··· (B). Using the length ratios such as La described above and these equations (A) and (B), the reaction force ratios of the vertical reaction forces of each of the wheels 24, 26, and 28 can be obtained.

[0030] For example, in the present embodiment, La:Lb is set to 1:2, and Fb1:Fa becomes 1:2. Also, in the present embodiment, Lc:Ld (=La) is set to 3:1 (as a result, Lc:Le = 1:1), and Fa + Fb1:Fb2 becomes 3:1. Combining these, the reaction force ratio can be obtained as Fa:Fb1:Fb2 = 2:1:1.

[0031] In this embodiment, this reaction force ratio means that when the rocker bogie mechanism is in a balanced state, the vertical reaction forces Fb1 and Fb2 acting on the driven wheels 26 and 28 are smaller than the vertical reaction force Fa acting on the drive wheel 24. This means that when the driven wheels 26 and 28 in the traveling direction try to climb over a step on the running surface 56, the link members 38 and 40 can swing more easily so that the driven wheels 26 and 28 rise, compared to the case where the vertical reaction force Fa and the vertical reaction forces Fb1 and Fb2 are made the same. As a result, it becomes easier for the driven wheels 26 and 28 to climb over the step on the running surface 56. In addition to this, by making the vertical reaction forces Fb1 and Fb2 smaller than the vertical reaction force Fa, while enhancing the tractability of the drive wheel 24 to which power is transmitted from the drive device 20, the rising operation of the driven wheels 26 and 28 that follow the shape of the running surface 56 can be lightened. As a result, the traversability over rough terrain can be enhanced. Here, the rough terrain includes not only locations with irregularities such as unevenness and steps, but also slippery locations.

[0032] Thus, when using the rocker bogie mechanism, in terms of design, the length ratio such as La is set to a predetermined length ratio so that the vertical reaction force acts on each of the wheels 24, 26, and 28 at the target reaction force ratio.

[0033] Here, the first swing axis 44 is not on the same vertical line as the rotation axis 70. This means that the first swing axis 44 is offset in the front-rear direction X with respect to the rotation axis 70. The first swing axis 44 of the present embodiment is located closer to the first driven wheel 26 side than the rotation axis 70. This is a necessary condition for realizing the length ratio regarding La:Lb described above.

[0034] When overcoming the step on the running surface, a large load is applied to the first support bearing 42. To resist this large load, it is necessary to increase the size of the first support bearing 42. If the first swing shaft 44 is arranged below the rotation shaft 70 in the vertical direction (up and down direction Z), the first swing shaft 44 and the first support bearing 42 will be too close to the running surface 56, and the dimensions of the first support bearing 42 will be restricted. To prevent this, the first swing shaft 44 is located above the rotation shaft 70 in the vertical direction (up and down direction Z). As a result, it becomes difficult for the dimensions of the first support bearing 42 to be restricted by the running surface 56, and the dimensions of the first support bearing 42 can be increased. Consequently, it is possible to easily ensure the durability required for the first support bearing 42 to resist the large load applied when overcoming the step.

[0035] The first swing shaft 44 is located inside the outer shape of the drive wheel 24. The first swing shaft 44 is located radially inside the drive wheel 24 (on the rotation shaft 70 side) from the outer peripheral surface 24a of the drive wheel 24 when viewed in the left - right direction Y. As a result, compared with the case where the first swing shaft 44 is located on the first driven wheel 26 side (the left side of the paper in FIG. 3) in the front - rear direction X from the end 24b on the first driven wheel 26 side of the drive wheel 24, the distance La from the rotation shaft 70 to the first swing shaft 44 can be shortened. The shorter the distance La can be made, the shorter the distance Lb required to maintain the length ratio La:Lb can be made. At the same time, by shortening these distances La and Lb, the distance Lc required to maintain the ratio Lc:Ld can also be shortened. Consequently, while maintaining a predetermined length ratio for La, etc., the overall front - rear dimension of the undercarriage device 14 can be reduced. The fact that a predetermined length ratio for La, etc., can be maintained means that the target reaction force ratio can be maintained regarding the way the reaction forces act on each wheel 24, 26, 28.

[0036] The effects of the above - mentioned undercarriage device 14 will be described.

[0037] (A) The leg mechanism 14 defines the predetermined positional relationship with respect to the drive wheels 24 and the first swing shaft 44. Therefore, in the leg mechanism 14 using the rocker bogie mechanism, it is possible to reduce the front - rear dimension of the leg mechanism 14. In order to achieve this, as described above, a predetermined length ratio can be maintained with respect to La and the like. In addition, as described above, it is also possible to ensure the durability required for the first support bearing 42 when crossing a step.

[0038] (B) The leg mechanism 14 includes a rotation support mechanism 62 that rotatably supports the driven wheels 26 and 28 around the rotation shaft 60. Therefore, when the leg mechanism 14 attempts to change the traveling direction, the driven wheels 26 and 28 can rotate following the change, and the followability when changing the traveling direction becomes good.

[0039] The rotation support mechanism 62 is individually provided corresponding to each of the first driven wheel 26 and the second driven wheel 28. Therefore, when the rotation directions of the left and right drive wheels 24 are reversed, ultra - tight turning can be achieved.

[0040] Note that the first support bearing 42 that connects the bogie link member 38 and the rocker link member 40 is located at a position shifted toward the first driven wheel 26 side in the front - rear direction X with respect to the rotation shaft 70. Therefore, between the first support bearing 42 and the rotation shaft 70, a structure is formed in which a part of the rocker link member 40 and a part of the bogie link member 38 overlap vertically. For this reason, compared with the case where the first support bearing 42 is on the same vertical line as the rotation shaft 70, the front - rear dimension of the entire leg mechanism 14 can be reduced.

[0041] Next, other features of the leg mechanism 14 of the present embodiment will be described. In the present embodiment, the outer diameter ratio between the drive wheel 24 and one of the first driven wheel 26 and the second driven wheel 28 is 2:1 or more. This condition is satisfied between the drive wheel 24 and the first driven wheel 26, and is also satisfied between the drive wheel 24 and the second driven wheel 28 in the present embodiment. The outer diameter here refers to the outer diameter in terms of the radius. Let the outer diameter of the drive wheel 24 be R24, the outer diameter of the first driven wheel 26 be R26, and the outer diameter of the second driven wheel 28 be R28. This means that R24:R26 is 2:1 or more, and R24:R28 is 2:1 or more.

[0042] The larger the outer diameters R26 and R28 of the driven wheels 26 and 28 are, the larger the overall front-rear dimension of the leg mechanism 14 becomes in order to maintain a predetermined length ratio regarding La and the like. For example, as the outer diameter R26 of the first driven wheel 26 increases, it is necessary to increase the front-rear dimension of the bogie link member 38 to increase the distance Lb in order to avoid interference with the drive wheel 24. Along with this, in order to maintain the ratio of La:Lb, it is necessary to increase the distance La as well. Furthermore, in order to maintain the ratio of Lc:Ld, it is necessary to increase the distance Lc as well. As a result, the overall front-rear dimension of the leg mechanism 14 becomes larger.

[0043] Also, the larger the outer diameter R28 of the second driven wheel 28 is, the larger the front-rear dimension of the rocker link member 40 needs to be to increase the distance Lc in order to avoid interference with the drive wheel 24. Along with this, in order to maintain the ratios of Lc:Ld and La:Lb, it is necessary to increase the distances La (=Ld) and Lb as well. As a result, the overall front-rear dimension of the leg mechanism 14 becomes larger.

[0044] In this regard, by satisfying the above-mentioned condition regarding the outer diameter ratio, compared with the case where this is not satisfied, the overall front-rear dimension of the leg mechanism 14 can be reduced while maintaining a predetermined length ratio regarding La and the like. Although the upper limit of the outer diameter ratio between the driven wheel and the drive wheel 24 is not particularly limited, for example, it may be 3 to 4:1 or less.

[0045] (Second Embodiment) Refer to FIGS. 5 and 6. The traveling device 10 of this embodiment is mainly different in the configuration around the first driven wheel 26 compared to the first embodiment. Since the configuration around the second driven wheel 28 is common with the first embodiment, the description here is omitted. When there is a driven wheel 26 to which power is not transmitted from the drive device 20 in the locker bogie mechanism, it becomes difficult for the driven wheel 26 to climb over a step 80 on the traveling surface 56. Hereinafter, the points of improvement for facilitating climbing over this step 80 will be described.

[0046] Refer to FIGS. 6 and 7. The wheel assembly 14 includes a lifting support mechanism 82 that supports the first driven wheel 26 in a liftable manner. The lifting support mechanism 82 is connected to the first driven wheel 26 in a liftable manner to the wheelbase 22. The lifting support mechanism 82 includes a wheel support 64 that supports the first driven wheel 26 rotatably around the axis 29 of the first driven wheel 26, and a lifting connection mechanism 84 that connects the wheel support 64 to the wheelbase 22 in a liftable manner.

[0047] The lifting connection mechanism 84 of this embodiment includes a linear bearing 86 attached to the wheelbase 22 (the bogie link member 38 in this embodiment), and a shaft 88 attached to the wheel support 64. The linear bearing 86 supports the shaft 88 in a linearly movable manner. The linear bearing 86 and the shaft 88 of this embodiment constitute a ball spline. The shaft 88 that constitutes the ball spline is a spline shaft having a plurality of splines. The linear bearing 86 that constitutes the ball spline includes an outer cylinder 86a attached to the wheelbase 22, and a plurality of balls (not shown) disposed between the splines of the shaft 88 and the outer cylinder 86a. The linear bearing 86 supports the shaft 88 in a non-rotatable and linearly movable manner in the axial direction by the rolling of the balls (not shown) between the outer cylinder 86a and the shaft 88. With the above-described lifting support mechanism 82, the first driven wheel 26 can be supported in a liftable manner along with the movement of the wheel support 64 in the vertical direction Z.

[0048] A shock absorbing member 90 such as a compression spring is disposed between the wheel base 22 and the wheel support 64. The load of the device main body 12 and the wheel base 22 is transmitted to the wheel support 64 and the first driven wheel 26 via the shock absorbing member 90. When an upward impact load is input to the first driven wheel 26, the shock absorbing member 90 elastically deforms, thereby absorbing the impact load. This in turn reduces the impact load transmitted to the device main body 12 of the traveling device 10.

[0049] The undercarriage device 14 includes an auxiliary wheel 92 that is positioned above and spaced apart from the flat running surface 56 when the first driven wheel 26 is in a state where it is in contact with the flat running surface 56. The auxiliary wheel 92 is disposed inside the first driven wheel 26 in the left-right direction Y. In this embodiment, the outer diameter of the auxiliary wheel 92 is larger than the outer diameter of the first driven wheel 26. The auxiliary wheel 92 is supported by the wheel support 64 so as to be rotatable about an axis 93 of the auxiliary wheel 92. The lifting support mechanism 82 supports the first driven wheel 26 and the auxiliary wheel 92 so that they can be lifted and lowered together. The auxiliary wheel 92 protrudes from the first driven wheel 26 on the opposite side of the second driven wheel 28 in the fore-and-aft direction X (here, forward) (see also FIG. 5 ).

[0050] The rotation support mechanism 62 corresponding to the first driven wheel 26 supports the first driven wheel 26 and the auxiliary wheel 92 so that they can rotate integrally around the rotation shaft 60. A part of this rotation support mechanism 62 also serves as a component of the lifting support mechanism 82. In detail, a wheel support body 64 and a shaft 88 (to be described later) of the rotation support mechanism 62 also serve as a component of the lifting support mechanism 82.

[0051] As described in the first embodiment, the rotational support mechanism 62 corresponding to the first driven wheel 26 includes a wheel support 64 that supports the first driven wheel 26 rotatably around the axis of the first driven wheel 26, and a rotational connection mechanism 66 that rotatably connects the wheel support 64 to the wheel base 22.

[0052] The wheel support 64 includes a first wheel support member 104 that supports the first driven wheel 26 and a second wheel support member 106 that supports the auxiliary wheel 92 .

[0053] The first wheel support member 104 includes a first fork 104a that supports the first driven wheel 26, and a second fork 104b that supports the first fork and is supported by the second wheel support member 106. The first driven wheel 26 of the present embodiment is supported by the first fork 140a of the first wheel support member 104 via an axle 108.

[0054] The second wheel support member 106 includes a plate-shaped second base portion 106a and a plate-shaped second support portion 106b that extends downward from the second base portion 106a. The first wheel support member 104 is fixed to the second base portion 106a of the second wheel support member 106. The second support portion 106b supports the auxiliary wheel 92 via an axle 110.

[0055] The rotation connection mechanism 66 of the present embodiment includes a shaft 88 attached to the wheel base 22 and a rotary bearing 112 disposed between the shaft 88 and the wheel support 64 and rotatably connecting the wheel support 64 to the shaft 88.

[0056] The rotary bearing 112 includes an inner ring 112a and an outer ring 112b, and a plurality of rolling elements 112c that roll between the inner ring 112a and the outer ring 112b. The shaft 88 of the present embodiment is fixed to the inner ring 112a of the rotary bearing 112 via a bearing holder 114 attached to the lower end portion of the shaft 88. The rotary bearing 112 of the present embodiment is housed in a recess 64a provided in the upper surface portion of the wheel support 64, and its outer ring 112b is fixed to the inner peripheral portion of the recess 64a.

[0057] The above-described rotation support mechanism 62 rotates the first driven wheel 26 by rotating the wheel support 64 around the rotation axis 60 that extends vertically through the axis of the shaft 88 with respect to the wheel base 22. The above-described rotation support mechanism 62 integrally supports the first driven wheel 26 and the auxiliary wheel 92 so as to be rotatable around the rotation axis 60.

[0058] The shaft 88 of the rotational support mechanism 62 in this embodiment also serves as a component of the lifting support mechanism 82, and is attached to the wheel base 22 via a linear bearing 86 used in the lifting support mechanism 82. If the shaft 88 of the rotational support mechanism 62 does not also serve as a component of the lifting support mechanism 82, it may be attached to the wheel base 22 so as to be non-linearly movable, without using the linear bearing 86. The shaft 88 of the lifting support mechanism 82 also serves as a component of the rotational support mechanism 62, and is rotatably attached to the wheel support 64 via a rotary bearing 112 used in the rotational support mechanism 62. If the shaft 88 of the lifting support mechanism 82 does not also serve as a component of the rotational support mechanism 62, it may be attached to the wheel support 64 so as to be non-rotatable.

[0059] The operation of the above-described training wheel 92 will now be described. Reference is made to FIG. 8(A). FIG. 8 schematically shows only the positions of the first driven wheel 26, the training wheel 92, and the rotating shaft 60. Consider a case in which the traveling device 10 travels with the direction of travel opposite the second driven wheel 28 relative to the first driven wheel 26 (here, the front side; the right side of the paper in FIG. 8(A)). In this case, the training wheel 92 protrudes on the opposite side of the second driven wheel 28 in the front-to-rear direction X, and therefore, as shown in FIG. 8(B), the training wheel 92 can climb up a step 80 on the traveling surface before the first driven wheel 26. In this case, as described above, the training wheel 92 is positioned above and spaced apart from the flat traveling surface 56, and therefore can climb up a high step 80 more easily than when the training wheel 92 comes into contact with the traveling surface 56.

[0060] After the auxiliary wheel 92 has climbed up onto the step 80, as the traveling device 10 continues to move forward in the traveling direction, the first driven wheel 26 can climb up onto the step 80, as shown in Fig. 8(C). As a result, it becomes possible to easily climb up onto a step 80 that is higher than the maximum step that can be climbed up by the first driven wheel 26 alone, using the auxiliary wheel 92 and the first driven wheel 26.

[0061] When the training wheel 92 climbs up the step 80, the link members 38, 40 of the rocker bogie mechanism oscillate around the oscillating shafts 44, 50 in response to the movement. 8(A) to 8(C) show the swinging of the link members 38, 40 by showing the change in the tilt of the turning shaft 60. As a result, while the training wheel 92 is climbing up the step 80, although not shown, the drive wheel 24 and the second driven wheel 28 are in contact with the running surface 56, and the training wheel 92 is in contact with the step 80 on the running surface 56 instead of the first driven wheel 26. In other words, even when the training wheel 92 climbs up the step 80, the three wheels (the training wheel 92, the drive wheel 24, and the second driven wheel 28) can maintain contact with the running surface 56.

[0062] The effects of the above-described suspension device 14 will now be described.

[0063] (C) The undercarriage device 14 includes a lifting support mechanism 82 that supports the first driven wheel 26 so that it can be raised and lowered. This allows the first driven wheel 26 to move up and down in accordance with steps 80 on the running surface 56, thereby increasing the maximum height of steps 80 that can be climbed by the first driven wheel 26.

[0064] (D) The undercarriage unit 14 is provided with training wheels 92 positioned away from the running surface 56. Therefore, the combination of the training wheels 92 and the driven wheels 26 allows the vehicle to overcome steps that are higher than the highest step that can be overcome by the driven wheels 26. If the driven wheels 26 were made larger to overcome such a high step, the overall front-to-rear dimension of the undercarriage unit 14 would increase in size in order to maintain a predetermined length ratio for the aforementioned La, etc. In this regard, according to the present embodiment, it is not necessary to increase the size of the driven wheels 26 to overcome a high step, and as a result, it is possible to avoid an increase in the overall front-to-rear dimension of the undercarriage unit 14.

[0065] (E) The rotational support mechanism 62 of this embodiment supports the first driven wheel 26 and the training wheel 92 so that they can rotate integrally. Therefore, when the undercarriage device 14 attempts to change its direction of travel, the first driven wheel 26 and the training wheel 92 can be rotated integrally while keeping the steering angles (directions) of the first driven wheel 26 and the training wheel 92 aligned in accordance with the change. Therefore, regardless of whether the undercarriage device 14 is traveling straight or on a curve, the training wheel 92 can climb up a step while keeping the steering angles of the first driven wheel 26 and the training wheel 92 aligned, and smooth operation can be maintained before and after climbing up the step.

[0066] (F) The lifting support mechanism 82 of this embodiment supports the first driven wheel 26 and the auxiliary wheel 92 so that they can be raised and lowered together. Therefore, the first driven wheel 26 and the auxiliary wheel 92 can be raised and lowered together to follow the steps of the running surface 56, and the height that can be climbed by the first driven wheel 26 and the auxiliary wheel 92 can be further increased.

[0067] Next, variations of the components described above will be described.

[0068] In the embodiment, an example has been described in which the first driven wheel 26 is a front wheel located on one side (front side) in the fore-and-aft direction X, and the second driven wheel 28 is a rear wheel located on the other side (rear side) in the fore-and-aft direction X. Alternatively, the first driven wheel 26 may be a rear wheel located on one side (rear side) in the fore-and-aft direction X, and the second driven wheel 28 may be a front wheel located on the other side (front side) in the fore-and-aft direction X.

[0069] In the first embodiment, an example has been described in which the length ratios of La and the like are set so that the vertical reaction forces Fb1 and Fb2 are smaller than the vertical reaction force Fa. The relationship between this length ratio and the reaction force ratio is not particularly limited. For example, the length ratios of La and the like may be set so that the vertical reaction forces Fa, Fb1, and Fb2 acting on the wheels 24, 26, and 28 are equal. To achieve this, for example, La:Lb in FIG. 3 may be set to 1:1, and Lc (=La):Ld may be set to 1:2.

[0070] Furthermore, in order to make the vertical reaction forces Fb1 and Fb2 acting on the driven wheels 26 and 28 smaller than the vertical reaction force Fa acting on the drive wheel 24, the length ratios such as La are not limited to those described in the embodiment. For example, in order to make the vertical reaction force Fb1 of the first driven wheel 26 smaller than the vertical reaction force Fa of the drive wheel 24, La:Lb may be set to 1:X (X is a value greater than 1). Although X is set to 2 in the embodiment, X may be set to any value greater than 1. As a result, it is possible to make Fb1:Fa 1:X from equation (A), that is, to make the vertical reaction force Fb1 smaller than the vertical reaction force Fa. In this case, Lc:Ld may be set to 1+X:1 (resulting in Lc:Le being 1:1). As a result, it is possible to make Fa:Fb1:Fb2 X:1:1 from equations (A) and (B). That is, it is possible to make both vertical reaction forces Fb1 and Fb2 smaller than the vertical reaction force Fa. Here, an example has been described in which both vertical reaction forces Fb1 and Fb2 are smaller than vertical reaction force Fa, but the length ratios such as La may also be set so that at least one of vertical reaction forces Fb1 and Fb2 is smaller than vertical reaction force Fa.

[0071] The rotation support mechanism 62, the lift support mechanism 82, and the training wheels 92 described in the embodiment are not essential, and the undercarriage device 14 may not include one or more or all of them.

[0072] The rotation support mechanism 62 is not particularly limited as long as it can rotatably support the driven wheels 26, 28. Furthermore, in relation to the effect (B) described above, the rotation support mechanism 62 only needs to be provided for either the first driven wheel 26 or the second driven wheel 28. It can also be said that the undercarriage device 14 is only required to be provided with a rotation support mechanism 62 that rotatably supports one of the first driven wheel 26 and the second driven wheel 28.

[0073] The wheel support 64 is only required to support the driven wheels 26, 28 so that the driven wheels 26, 28 can rotate about the axes of the driven wheels 26, 28, and the specific configuration thereof is not particularly limited.

[0074] In the above description, the lifting support mechanism 82 supports the first driven wheel 26 so that it can be raised and lowered. In addition, in relation to the effect (C) described above, the lifting support mechanism 82 may support the second driven wheel 28 so that it can be raised and lowered. The lifting support mechanism 82 only needs to support one of the first driven wheel 26 and the second driven wheel 28 so that it can be raised and lowered. In this case, the matters described in the embodiment can be embodied by replacing the first driven wheel 26 with the second driven wheel 28.

[0075] When the linear bearing 86 is used in the lifting connection mechanism 84 of the lifting support mechanism 82, there are no particular limitations on the specific example of the linear bearing 86, and it may be, for example, a slide bush, etc. Alternatively, the lifting connection mechanism 84 of the lifting support mechanism 82 may be a guide mechanism such as a linear guide, in addition to the combination of the linear bearing 86 and the shaft 88.

[0076] Although the example has been described in which the wheel support 64 of the lifting support mechanism 82 supports the auxiliary wheels 92 in addition to the driven wheels 26, it may also support only the driven wheels 26 without supporting the auxiliary wheels 92. In this case, the effect (C) described above can also be obtained. Furthermore, although the example has been described in which the lifting support mechanism 82 supports the first driven wheels 26 and the auxiliary wheels 92 so that they can be raised and lowered together, it may also support the second driven wheels 28 and the auxiliary wheels 92 so that they can be raised and lowered together.

[0077] In the first embodiment, an example was described in which the training wheel 92 is provided corresponding to the first driven wheel 26 and protrudes from the first driven wheel 26 on the side opposite the second driven wheel 28 to the first driven wheel 26 to achieve the effect (D). To achieve the same effect, the training wheel 92 may be provided corresponding to the second driven wheel 28 and protrude from the second driven wheel 28 on the side opposite the first driven wheel 26 to the second driven wheel 28. The training wheel 92 only needs to protrude from one of the first driven wheel 26 and the second driven wheel 28 on the side opposite the other driven wheel in the front-to-rear direction X. In this case, when the traveling device 10 travels with the direction of travel opposite the first driven wheel 26 to the second driven wheel 28, the same effect as the above-described (D) can be achieved. Alternatively, the training wheels 92 may be provided individually corresponding to the first driven wheel 26 and the second driven wheel 28, respectively.

[0078] The outer diameter ratio between the drive wheel 24 and one of the first driven wheel 26 and the second driven wheel 28 may be less than 2:1. Also, only the outer diameter ratio between the drive wheel 24 and one of them may be 2:1 or more, and the outer diameter ratio between the drive wheel 24 and the other driven wheel may be less than 2:1.

[0079] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the content of the embodiments and modified forms. Many design changes such as changes, additions, and deletions of components are possible for the content of the embodiments and modified forms. In the foregoing embodiments, with regard to the content for which such design changes are possible, the notation "embodiment" is attached for emphasis. However, design changes are also permitted for the content without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached. The structures / values mentioned in the embodiments and modified forms naturally include those that can be regarded as the same in consideration of manufacturing errors and the like.

Explanation of Reference Numerals

[0080] 10... traveling device, 12... device main body, 14... undercarriage device, 24... drive wheel, 26... first driven wheel, 28... second driven wheel, 38... bogie link member, 40... locker link member, 44... first swing shaft, 50... second swing shaft, 56... running surface, 60... rotation shaft, 62... rotation support mechanism, 82... lifting support mechanism, 92... auxiliary wheel.

Claims

1. A drive wheel, a first driven wheel disposed on one side in the front-rear direction with respect to the drive wheel, a second driven wheel disposed on the other side in the front-rear direction with respect to the drive wheel, a bogie link member that supports the drive wheel and the first driven wheel and is swingable around a first swing axis, a rocker link member that supports the second driven wheel and the bogie link member and is swingable around a second swing axis, an auxiliary wheel positioned away from the running surface when one of the first driven wheel and the second driven wheel is in contact with the running surface, and when viewed from the left-right direction, the first swing axis is not on the same vertical line as the rotation axis of the drive wheel, is positioned above the rotation axis in the vertical direction, and is positioned inside the outer shape of the drive wheel, the auxiliary wheel is a running gear that protrudes to the opposite side in the front-rear direction from the other of the first driven wheel and the second driven wheel with respect to the one driven wheel.

2. The running gear according to claim 1, further comprising a rotation support mechanism that rotatably supports one of the first driven wheel and the second driven wheel around a rotation axis extending vertically.

3. The running gear according to claim 1 or 2, further comprising a lifting support mechanism that supports one of the first driven wheel and the second driven wheel so as to be liftable.

4. The running gear according to any one of claims 1 to 3, further comprising a rotation support mechanism that rotatably supports the one driven wheel and the auxiliary wheel around a rotation axis extending vertically integrally.

5. The running gear according to any one of claims 1 to 4, further comprising a lifting support mechanism that supports the one driven wheel and the auxiliary wheel so as to be liftable integrally.

6. The running gear according to any one of claims 1 to 5, wherein an outer diameter ratio between the drive wheel and one of the first driven wheel and the second driven wheel is 2:1 or more.

7. A device body, a running device comprising the running gear according to any one of claims 1 to 6 attached to the device body.

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